The present invention relates to minute structures for producing colors which are applied to fabrics, coating fibers and chips, etc. The present invention also relates to spinnerets for manufacturing the minute structures.
Conventionally, a method of adopting inorganic or organic dyes and pigments or scattering bright members such as aluminum and mica flakes in paints has been in general use for providing various fibers and car coatings with desired colors or improved visual quality.
Recently, with an user's tendency to a high fabric quality, etc., there are increasing demands on graceful and quality minute structures which have tones varying with a change in the angle of view and having high chromas. Some minute structures are developed and proposed to satisfy the above demands. One is such as to produce a color by reflection, interference, diffraction or scattering of light without using coloring matters such as dyes and pigments. The other is such as to produce a brighter color by combining the above optical action and the dyes and pigments.
JP 43-14185 and JP-A 1-139803 disclose coated-type composite fibers with iridescence which are made of two or more resins having different refractive indexes.
A journal of the Textile Machinery Society of Japan (Vol. 42, No. 2, pp. 55-62, published in 1989 and Vol. 42, No. 10, pp. 60-68, published in 1989) describes laminated photo-controllable polymer films for producing colors by optical interference, wherein a film with anisotropic molecular orientation is interposed between two polarizing films.
JP-A 59-228042, JP-B2 60-24847 and JP-B2 63-64535 disclose fabrics with iridescence conceived, e.g. from a South American morpho-butterfly which is well-known by its bright tone varying with a change in the angle of view.
JP-A 62-170510 and JP-A 63-120642 disclose fibers and sheetlike articles which produce interference colors due to recesses with a predetermined width formed on the surface thereof, respectively. Each document describes that formed objects are fast and permanent in color due to no use of dyes and pigments.
The minute structures as disclosed in JP 43-14185 and JP-A 1-139803 have an advantage of producing colors irrespective of the incident direction of light, but are imperfect in view of tone brightness and visual quality due to the fact that the optical thickness (geometrical thickness of a covering layer x refractive index thereof is not always constant when viewed from the incident direction of light.
The minute structure as described in the journal of the Textile Machinery Society of Japan is difficult to be formed in fine fibers and minute chips or pieces, and are still imperfect in view of tone brightness.
The minute structures as disclosed in JP-A 59-228042, JP-B2 60-24847, JP-B2 63-64535, JP-A 62-170510, and JP-A 63-120642 are difficult to give desired coloring function due to no precise teachings of the dimension thereof.
For solving such inconveniences, U.S. Pat. No. 5,407,738 and U.S. Pat. No. 5,472,798 propose new minute structures, with concrete dimension, for producing colors which have bright tones varying with a change with the angle of view by reflection and interference of light, and no change with time. The teachings of U.S. Pat. No. 5,407,738 and U.S. Pat. No. 5,472,798 are hereby incorporated by reference.
The minute structures as disclosed in U.S. Pat. No. 5,407,738, which produce colors by reflection and interference of light, i.e. when satisfying the interference condition with regard to the refractive index and thickness of two component substance layers, are inferior in diversity than the conventional minute structures comprising generally coloring matters which can produce various colors by mixing coloring matters of different kinds.
Moreover, the above minute structures, which are made of materials having optical penetrability, may be out of the coloring condition when contacting a transparent substance layer, not determined. That is, when an environment of the minute structures is determined to be an air layer, the phenomenon occurs that the above minute structures give excellent coloring function in the air layer, but do not give sufficient coloring function in an environment with no air layer.
By way of example, when clothes made of fibers of minute structure are wet with oil (refractive index n=1.34 to 1.54) or water (refractive index n=1.33), or put in a solvent, the clothes have a substance layer with different refractive index formed on the fiber surface, etc., resulting in no production of desired colors, and occasionally, an occurrence of see-through.
Therefore, an object of the present invention is to provide minute structures of high quality which produce, by reflection and interference of light, colors with various bright and clear tones and without any possible occurrence of see-through.
Another object of the present invention is to provide spinnerets for manufacturing the above minute structures.